This invention relates to a disk mower to be pulled by a farm tractor, and more particularly the power transmission mechanism thereof.
Disk mowers are provided with a plurality of cutter members arranged on a slender cutter frame which extends in the lateral direction, and are utilized for harvesting grass in meadows. Since, in the disk mower, cutter members are mounted at right angles on a driving shaft inserted in the cutter frame and, further, a disk provided with a cutter blade is rotated at high speed (generally 3000 rpm) to sever grass, the slender and long-extended cutter frame has a tendency to be waved and/or twisted during operations due to the vibration at the time of cutting. These deformations of the cutter frame are transmitted to the power transmission part of the disk as impact force so that the power transmission part receives excess load, which sometimes results in damage. Studies to overcome this defect has been undertaken in the past. One of them is to increase the rigidity of the cutter frame to prevent the deformations, by the strength of materials. This approach resulted in, however, the increase of weight and cost of the products, so that it is necessary to find a solution which does not result in the increase of weight and cost. In this connection, for instance, such solutions have been proposed as increasing backlash of the gears to absorb the deformations of the cutter frame, or as making the teeth of the gears large-sized to increase the accuracy of the supporting part of the gears. Australian Pat. No. 491002 disclosed this kind of solution. The former one generates, however, large noise while the latter introduces complex construction difficulty in maintenance and/or high product costs. Particularly, the maintenance problem is important because daily checks and/or adjustments have been carried out by disassembling the cutter frame in the past.